The present invention relates to handwriting capture devices and more specifically to a handwriting capture system with a segmented digitizer.
An example of a conventional four-wire membrane digitizer is the Bradytouch digitizer panel from Dynapro Thin Films Division of Milwaukee, Wis. An example of a conventional five-wire membrane digitizer is the AccuTouch digitizer panel from Elographics of Oak Ridge, Tenn.
Conventional membrane digitizers are ideal in applications that require sensitivity to both stylus and finger, low cost, and a passive stylus. "Passive stylus" is one which has no electronics or moving parts.
Unfortunately, conventional membrane digitizers also have several drawbacks. Chief among them is its lack of "hand rejection", which is the ability to ignore a user's hand while the user is writing with a stylus. Touching the digitizer with a finger while writing with a stylus yields unpredictable digitizer data.
Two ways are known to reduce the hand rejection problem. One is to detect and then completely reject any points gathered while the user is touching with both a finger and a stylus. This method is useful in many situations, but it has the disadvantage that it cannot accurately digitize stylus position while the user is touching with a finger. The other prior art solution is to mechanically optimize the digitizer for only stylus actuation by making the spacer dots of the digitizer closer together. This solution is not acceptable in most situations because it requires an uncomfortably high stylus actuation force.
Therefore, it would be desirable to provide a handwriting capture system with a segmented digitizer which is largely immune to finger or hand contact.